Boric acid-diol-alcohol additive and liquid leaded motor fuel containing same



United States Patent G BORIC ACID-DIOL-ALCOHOL ADDITIVE AND lQUID LEADED MOTOR FUEL CONTAINING John I). Bartleson, Franklin, Mich., and Robert B. Faris, Jr., Solon, Ohio, assignors to The Standard Gil Company, Cleveland, Ohio, a corporation of Ohio 1 Claim. (CI. 44-56) No Drawing.

The present invention relates to a boric acid-diol-monohydric alcohol solution suitable as an additive to liquid leaded motor fuel, to liquid leaded motor fuel for use in internal combustion engines of the spark-ignition type, said fuel containing a minor proportion of such an additive, and to a method of operating spark-ignition internal combustion engines in such manner as to suppress the octane requirement increase normally resulting from operation of such engines.

It is well known that the operation of an internal combustion engine, initially clean, results in a formation of progressively greater amounts of deposits on the surfaces of the combustion zone, i.e., on the cylinder head, piston top and the intake and exhaust valves, until the amount of deposits reaches a level beyond which no appreciable further increase in amount of deposits are apparent upon continued operation. This increase in deposits is manifested most clearly to the operator of the engine, particularly an automobile engine, by the fact that the presence of the deposits in the engine requires a fuel having a higher octane rating in order not to knock than is required by a new or clean engine. This means, in other words, that the octane value of a fuel required by an engine containing deposits in the combustion zone in order not to knock (referred to hereinafter as octane requirement) is higher than the octane requirement of a clean engine. For example, a clean engine which requires a gasoline having an octane rating of 60 in order not to knock is said to have an octane requirement of 60. If the same engine, when dirty, i.e., with deposits in the combustion chamber, requires a gasoline having an octane rating of 75 in order not to knock, such an engine is said to have an octane requirement of 75 or an octane requirement increase of 15. When upon continued use the octane requirement of the engine increases no further, it is believed that the engine has then reached deposit equilibrium. This is believed to be due to the fact that after a certain amount of deposits have been formed in the combustion zone, additional amounts of deposits either fail to adhere to the deposits already formed or the rate of formation of additional deposits becomes about equal to the rate at which the deposits flake off and are removed through the exhaust of the engine. These deposits also result in power loss, valve deterioration, and other undesirable effects in engine operation.

The undesirable effects of the deposits in the combustion zone is further aggravated when tetraethyl lead is contained in the fuel in amounts varying between about 0.5 and 6 cc./gal., e.g., about 3 cc./gal., because these deposits are then no longer primarily carbonaceous but contain appreciable quantities of lead or lead compounds. It has been sought to overcome this additional disadvantage due to the use of tetraethyl lead by add-ingone or' more organic halides to the fuel so that, during the combustion, the lead from the-tetraethyl lead will combine with the halogen from the organic halide to form a lead halide that will pass out of the engine through the ex- Patented Mar. 22, 1960.

.formed in the combustion zone is appreciably greater when using a leaded fuel than when using a non-leaded fuel. The octane requirement increase of an engine operating onleaded fuel, however, is not in proportion to the difference in deposit weights. From this it is concluded that the octane requirement increase of an engine is not determined so much by the quantity of material deposited as by its presence and character.

Since it has been found that the octane requirement increase of an engine is not determined solely by the quantity of material deposited in the combustion zone, it is believed that it is due to a catalytic action wherein the deposits in the combustion zone act as catalysts to accelerate the oxidation of petroleum hydrocarbons. The fact that lead compounds have greater catalytic activity than carbon in accelerating the oxidation of petroleum hydrocarbons is believed to account for the greater increase in the octane requirement of an engine operated on leaded fuel as compared with that of an engine operated on non-leaded fuel. It was, therefore, believed that the proper approach to the problem of reducing the octane requirement increase of an engine was that of adding to the fuel a substance having an anticatalytic effect or, in other words, the effect of suppressing or inhibiting the catalytic properties of the deposits formed, especially the troublesome lead-containing deposits.

It was found, as described in the application of Everett C. Hughes and John D. Bartleson, Serial No. 313,788, filed October 8, 1952, and now abandoned, that it is possible to suppress, to a considerable degree, the octane requirement increase of an engine and to reduce materially the equilibrium amount of deposits formed in the engine, particularly on the exhaust valve, by operating such an engine with a leaded motor fuel containing a fuel-soluble additive consisting essentially of an alcohol having boric acid dissolved therein, preferably in maximum concentration. While alcohol-boric acid mixtures of this type have been demonstrated to be fairly stable in the fuel when subjected to moderately cold temperatures such as 40 F. and even in the presence of 0.02% and 0.04% by volume of water based on the volume of the blended fuel (the upper limit of solubility of water in gasoline), the stability of the boric acid-alcohol additive leaves something to be desired when free water becomes mixed with the fuel or when the fuel is under a water saturated atmosphere for any extended period of time. Unless precautions are observed to remove the water that accumulates in gasoline storage tanks due to condensation of moisture on the Walls, these disadvantages of the boric acid-alcohol additive may become significant. Thus, for example, the presence of water in the tank may result in substantial, if not complete transfer of the boric acid from the fuel to the water.

The present invention is based on the surprising discovery that the presence of a relatively small amount of alcohol that is required to dissolve the optimum effective amount of boric acid. When the maximum V 1 Inasmuch as essentially a boric acid-diol-monohydric alcohol solution. A leaded liquid fuel containing this additivein minor concentration is particularly adapted for use in an initially clean engine although when used in a dirty engine it would have a gradual beneficial effect. The

term initially clean, as applied to an engine herein, is intended'to refer to an engine thatwas new or had I most or substantially all its combustion chamber deposits removed by scraping, grindingflshot injection, or like methodswhen operation of, the engine on the fuel of the invention was begun. 7

The diol component of the additive of this invention is a non-benzenoiddiol containing from four to about eight carbon atoms. Examples of diols that have been found particularly effective in the additive and fuel of the invention are glycols such as diethylene glycol, polyethylene glycol 200,, hexylene glycols such as 2 -methyl-2,4 pentanediol, and 2= et-hyl, Z-butyl propanediol.

tests have shown that the amount of boron that is elfectivein suppressing octane requirement increase is extremely small, e.g., about 0.0018 to 0.008%, and preferably from 0.00410 0.008%, and no substantially greater effects are obtained with higher amounts capable of being dissolved by appropriately greater amounts of diol, the proportion of boric acid in the fuel is generally between about 0.01 and 0.045% by weight. Boric acid in the amount of 0.01, 0.02 and 0.045% correspond approximately to 0.0018, 0.004 and 0.008% by weight boron. There is no advantage in increasing the boric acid beyond 0.1%. The proportions of the diol component may vary rather wideiy, proportions between about 0.05 and 0.5% by weight of the fuel being generally desirable and proportions in the neighborhood of 0.1 and 0.2% being preferred.

The monohydric-alc'ohol component of the additive may .beiany alcohol that is soluble in the motor fuel,

volatile undercombustion chamber conditions, and is capable of dissolving the boric acid and the diol. it is preferably a lower alkylol. such as methyl-, ethyl-, isopropyl-, butylor amyl alcohol. Isopropyl alcohol is the least expensive and most easily obtained at this time.

the fuel blend that is necessary to dissolve an effective amount of borie acid and diol is as low as about 0.1%, but enhanced suppression of the octane requirement increase appears When the alcohol concentration in the fuel is in the range of about 0.5 to 1%. The slightly greater effects that may be obtainable with alcohol concentrations of above about 2% to about 5% are generally not preferred for reasons of economy but are nevertheless operable ranges of concentration.

In one embodiment referred to as the higlt alcohol formula, the amount of the alcohol is many times the amount of the diol. This formula is desirable when the octane requirement increases to be suppressed to the maximum extent. Such a formula is also suitable for use in the winter when the relatively large amount of alcohol will contribute to the antifreezing properties of the gasoline. v 7

In another embodiment, referred .to as the low alcohol formula, the amount of the alcoholmay be approximately the same as the amount of the .diol. This formula is entirely-satrsfacto from the standpoint'of solubility and stability of the boric acid in the gasoline. Itcan be used when moderate suppression of octane requirement increase is satisfactory andunder conditions where the excess alcohol cannot be justified economically,

The concentration of the alcohol component in 4- such as in the summertime when there is no antifreezing problem. Any amount of the alcohol between these two can be used.

Summarizing the preceding discussion with reference to the operable and preferred relative proportions of boric acid, diol andmonohydric alcohol in the additive and in the fuel, these proportions are approximately:

Boric Acid Diol Alcohol Alcohol (High) (Low) In the Additive (parts by 7 weight): V V

Operable 35-4. 5+ 1-35 65-99 1-35 Preferred 2-4 4. 5-10 -95 4. 5-10 In the Fuel (percent based on Total fuel)- Operable .01-.045+ .05-.5 1-5 .05-.5 Preferred 045 1-. 2 1-2 1-. 2

As illustrative of the high alcohol formula an additive was prepared containing 2.1% boric acid, 8.9% hexylene glycol, and 89% isopropanol. The additive wasprepared by stirring the ingredients forl /z hours at 30 F. The additive was stable at 0 F. and was readily blended with the gasoline. In'this example as well as all others in the case,the ingredients are essentially in a physical mixture. If there is any reaction it is slow and proceeds only to equilibrium conditions at ambient temperature since no water of reaction is removed. The amount of the monohydric alcohol is sufiicient to prevent any such water from separating when the mixture is added to gasoline.

This additive was incorporated in amounts of 0.5 and 1.0 volume percent in gasoline containing 3 cc. of tetraethyl lead and one theory of ethylene dichloride and one-half theory of ethylene dibrornide (motor mix) as a scavenging agent. Aslightly cloudy solution was at first formed, which cleared, however, on standing, with no loss of boric acid. Tests of these 'gasolines showed no lo'ss of boric aciddurin'g storage under moist air at 0 F., 75 F., and F. The additive did not affect any of the usual gasoline inspection tests and had no efiiect on oxidation stability or gum formation in storage. Tests show that it did not affect the corrosion of copper, steel or zinc die cast alloys. Gasoline containing the additive had no effect on hearing corrosion or varnish rating in an L-4 test, nor on sludge of varnish rating in the EX 3 test.

To compare the stability "of boric acid-alcohol and boric acid-diol-monohydric alcohol additives leaded motor gasoline in the presence of water vapo'r,.a number of tests were carried out in which samples of the gasoline containing 2% by Weight isopropyl-alcohol, 0.045% by weight boric acid (0.008%) boron, and diols in varying concentrations were allowed to stand for extended lengths of time in a desiccator-type vessel containing air saturated with water vapor. These samples were exarnined at various times, particularly after sixteen hours, to determine the extent, if any, to which the boric acid had formed crystals. The results of these tests are tabulated in Table'I immediately below:

TABLE I Concern. tration Time, Description of Diol in Fuel. Hours Crystals Formed Percent by wt.

- r 0.14 16 None. Polyethylene glycol 200 0A 55 Very few, flaky,

W t p 0.2 24 None. Drethylene g'lycol.;- -0. 14 16 Do.

r 0.1 65 Few. small.

. 0.1 16 None. 2 ethyl. 2 butyl propanedtoh; .0-1 65 Do. 5 65 S a 2 methyl=2,4 pentanediol;;-;-..-. 0. 2 22 None. N

22 Many, large.

The results of these tests show that the presence of small proportions of a diol in the additive elfectively prevents the formation of boric acid crystals. Such crystals, if formed in a gasoline storage tank, would de scend to the bottom of the tank and thus be lost to the fuel. The crystals either form a sediment on the bottom or, if water is present, enter the water layer to form a dilute boric acid solution. If, on the other hand, such crystals should form in or be carried to the fuel pump of an automotive engine of the gasoline tank they would collect on the fuel pump screen and soon clog it sulficiently to prevent further delivery of gasoline to the carburetor.

Another series of tests to compare the stability'of boric acid-alcohol and boric acid-diol-monohydric alcohol additives in leaded motor gasoline were carried out in a similar manner, the stability however being determined by measuring the a'rnoun'tof boric 'acidch'einiically extracted from the fuel sample-instead of by visual observation of crystal formation. In these tests the samples of the fuel, each containing 0.045% by Weight boric acid and allowed to stand for extended lengths of time in a desiccator-type vessel containing air saturated with water vapor, were subjected to extraction of the boric acid by treatment with a sodium hydroxide solution and, after adjusting the pH and removing carbon dioxide, determining the boron content by electrometric titration using mannitol. These tests are believed to be more accurate than visual tests in determining the percentage of boric acid retained in the fuel. The data obtained in these tests are tabulated in Table H immediately below:

the diol in keeping the'boroninthe gasoline 'phase'fas well as to prevent anygtendency of the boron to form crystalline boric acid under the conditions of the tests.

The utility and advantages of the invention will become further apparent from the following example illustrating the invention still more specifically, it being understood, however, that the example is not to be con sidered as limitative in scope:

Example Comparative test runs were conducted with a standard Chevrolet passenger car engine made initially clean after each run by dismantling, removing the combustion chamber'deposits, and reassembling. In each run the engine was operated on a standard cycle procedurewith an 11 spark advance to simulate city driving conditions. Each cycle included one minute at 500 r.p.m. with no load (idling conditions) and an air fuel ratio of 111.2, and five minutesat 2000 rpm equivalent to 40. mph; with 11.2- lbs. brake horsepower load, an air fuel ratio between 13.5 and 14.5, water outlet temperature of 165 F., water inlet temperature of 155 and oil sump temperature of 195 F. 100 hours of operation under this cycle is equivalent to approximately 4000 miles of city driving.

As indicated in Table III below, the comparative runs were made on initially clean engines with leaded gasoline containing 3.0 cc./gal. tetraethyl lead carried in a "motor mix containing 0.5 mole of ethylene bromide and 1.0 mole of ethylene chloride per mole of tetraethyl lead, and containing in addition additives consisting of from one to all three of the essential components of the additive of the present invention.

TABLE III Run No 1 2 a 4 5 6 7 8 Concentration, percent by wt., in

Fuel of:

Boron 0 .008 .004 .004 .008 .008 .000 Isopropanol 0 2.0 2.0 0.5 1.0 0.3 0.75 2 2-r ueth,vl-2.4 pentanediol. 0 0 0 0.1 0.1 0.2 0.1 0.2 Durahon of Run 146 100 99 103 118 103 198 124 Octane Requirements:

1 m] 7a 71 72 74.3 75.5 75 72 74 Final s4 s0 77 82.8 79.5 84' 84 79 Increas 0 5 8.5 4 9 -12 5 eposit wts.,

P1ston'lop 20.7 37.0 22.4 22.6 27.3 32.0 29.1 20.7 Exhaust Va1ve 23.8 4.2 3.4 3.95 4.2 ;5.0 at Valve 15.1 12.1 9.1 12.1 12.0 10.0

. TABLE H Comparison of the datain runs Nos. 1 and 2 shows that an additive consisting of 2.0% by weightof isoprof Additive cone.in P panol without boron or a diol has very little elfect in Gasoline ercent .Hmrs in Percent Percent H3130; suppressing the octane requirement lncrease and has the P Dcilc- B H 130; rg t ine d undesirable effect of increasing significantly the weight Percent ercent caor ue mm]... 1.0.... Poms on m 9 st varieties? pentanediol panol valve.

Comparison of the data in runs Nos. 1, 2, and 3 .1 2.0 10 0.0001 0.035 78 shows the eifectiveness of boron in combination with 3:52 g 8:88g 8:8; 23 isopropanol in both suppressing octane requirement in- .2 1.0 00 0. 007g 0. 041 00 crease and reducing the weight of deposits in the comg -g is I 8:3gg 8:33; 3: bustionchamber. It is apparent, therefore, that if proper, 0 2.0 I 0 0.0 72 0.045 precautions are observed to keep gasoline tanks reason; 8 5:8 ,3 8:8 5 -gfiga 5 ably free of water,- leaded gasoline treated with a boric 1 Crystals removed by filtering.

The results in Table II indicate that substantially all the boron initially present in the gasoline containing the additive of the present invention remained in the gasoline after being in contact with saturated air for periods of sixteen to ninety hours, whereas approximately 68% of the boric acid in the gasoline samples containing 2% isopropanol but no diol was removed from the fuel after eighteen hours and practically all was removed after ninety hours. The results also show that extremely small amounts of isopropanol, e.g., 0.3%, are suficient to inhibit crystallization and removal of the boric acid from the fuel and illustrate the remarkable stabilizing efiect of acid-containing additive not stabilized by the presence of; a diol would be elfective in suppressing the octane ref quirement increase of an engine.

Runs Nos. 4 to 8, inclusive, show the effects of various relative concentrations of boric acid, isopropanol and diol in leaded gasoline. In run No. 4 the boron is present in an eifective amount but the results indicate that the isopropanol, while present in an amount sufficient to insure stability of the boric acid, is not present in an amount suflicient to give optimum suppression of the octane requirement increase. In run No. 5 wherein the isopropanol content is increased to 1.0%, all other concentrations remaining the same, the octane requirement increase was held to only 4 in contrast with the it;

gr ases of 1.1 9,, 5 fi ld. 8-5 n uns Nos. 1. 3 an 4, res ectively- In runsN tive incre sed 7 and 8 t e boron co ten i the addito 0.008% (,045% boric acid) and the isopropanol and diol concentrations were varied.

Compar son o hese three uns indi a s as does a pari o o run .Nos 4 and itha the is p pe oncentration seems to play a part in suppressing the octane requirement increase, the 0.3 and 0.75% by weight concentrations being sufficient to-stabilize the boric acid but enflicien nly to suppress p rtly oc an q ir inma e addition it may be noted that under atmospheric condi io s of hi umidityt s s imi r o hose r p te in e exa p e sho n h t or e aci =c ntain ng add ti es which a no stab. de osi s. p domin y o o an he bu te y al of the carburetor and presumably also in portions of the intake h iiqlsli Th te a hi h these dep sit end to h tor ed isnet. owever. one hat appea to have any appreciable deleteriollt effect upon theability of the boric acid to suppress the octanejrequirernent increase of 'the engine. .The use of the diol-containing additives of the present invention is advantageous in that they have been found to be stable and do not'resnlt in the formation of any detectable deposits on the butterfly alve even hen e a r e e i he ar u to s a rated with water vapor. .Likewiseno detectable deposits containing additive is stabilized with a diol or not, when the air entering the carburetor is relatively dry.

A il ustrat cf an dd e of e lo a o t ne. an additive composition was prepared in the same man? ner containing 2.1 parts of bdrieaeid, 8.2 parts of hexylene glycol, and 8.9 parts of isopropanol. The glycol and the alcohol dissolved the boric acid upon heating and the additive was incorporatedin the gasoline in an amount to provide 0.023% boric acid in the gasoline. This addi'-' 'tive presented no difficulties in additive stability in storage and was as satisfactory as the previously described additive from the standpoint of maintaining the bori, acid i the lineh as in nta ccof tetraethy leadiin the motor rnix formula as described previously. asol e with an W t u t s di tested in 1951 Oldsmobile engines. The test involved-two cycles one a e he o he fi st ycl a for 49 econds at 500 rpm. with no beam load and no brake horsepower. The second cycle lasted 80 seconds at 1500 r.p;r n.','

h' e l o 3 Wind and 1 brake 59 p his test las ed 0. hQ'JI and he res l s a e shown in the following table: a a

3 'Fuel Blank plus Add ve Final Octane Requtrement. 90.0 87. 5 Octane Requirement Increase; 12.5 10. 0 Power Decrease at 1,500 r.'p.rn.}percent 37.9 3. 47

From the above table it will be seen that, while this additive does'not reduce the octane requirement increase as dramatically as some of the examples decribed pre niousl'y, this can be attributed to the'loweramouritof alcohol. The power is measured at the beginning of the test and at the end and the powerdecrease with the gasoilizedby a d ol tend to form e ned rega e s o h th r h Dor ac q n iific i n 8 additive is surprisingly small, as compared with the gasoline not containing the additive. This can beattributed to the improved character of the deposits which minimized yalve deterioration during the line conta n n e test and left the engine in excellent operating condition.

This same gasoline plus the additive was tested in cars which had been, run on gasoline notcontaining an additive, and were then switched to the gasoline containing the additive, following whichthe car was operated for the number of miles indicated in the table. The cars were tested at the beginning and end of'the mileage run for acceleration and for compression pressure, with the following results:

. V Decrease in Increase in Car Miles Accelera- Com restion Time, sion Prespercent sure, p.s.i.

1952 Buick" 594 2112 12. 6 1949 Packard '1, 231 16.6 9.6 1953 Ford 8, 252 14. 5 3. 0

The spark plug s'of all three cars were examined at the beginning and end of the test and in all instances were ated s fo t s i h y o in an n o c s was e f u si fi t mere evere at e nd f h .test than at the beginning.

' It is to be understood that various substitutions and wilLreadily occur to those skilled in the a upon reading t is e ripti nu h sub itutio s'a si mod i a h n ed t be nc uded Within th s ope of the invention as defined in the appended claim. 7

Thisapplication is a continuation-in-part of application Ser. No. 371,709, filed July 31, 1953, and now abandoned.

We claim: A motor fuel for internal combustion engines of the spark-ignition type, which fuel remains a stable and homogeneous solution in storage in the presence of atmospheric moisture consisting essentially of from 0.01 to 0.045% by weight boric acid, from 0.1 to 0.5% by weight a non-benzenoid diol containing from 4 to about 8 carbon atoms, from 0.05 to 5% by weight an alkyl monohydric alcohol containing up to about 5 carbon atoms, and the remainder being leaded gasoline.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Jan. 26, 1955 OTHER REFERENCES Giycolsfl Carbide and .Carbon Chem. Corp., March 31, 19.47. pp. 394 and'S.

Ind. &' Eng. Chem,

vol. 43, pp. 2841-44, December 

